It has long been recognized that if the hydrogen on earth were readily accessible it could become a major and virtually unlimited source of energy. For example, when cooled and liquified, it could serve as fuel for modified internal combustion engines and when passed through fuel cells, it could generate electricity.
However, most of the hydrogen found on the earth is bound with oxygen in the form of water. For this reason, there have been numerous attempts to develop techniques of splitting water into its two components, hydrogen and oxygen. Most recently, attempts have been made to achieve such splitting by photosynthesis. In one such arrangement, spinach chloroplasts are placed in a solution containing various substances including enzymes which speed up the reaction. In effect the energy of the sun is captured by the chloroplasts which use the energy to disassociate a molecule of water into its component parts, hydrogen and oxygen. This technique, although promising, has not as yet proven feasible for commercial applications.
It has been known for many years that water can be split by electrolysis whereby an electric current passed through water breaks the bond between the hydrogen and oxygen atoms in the water molecules thereby releasing hydrogen as well as oxygen. However, it has not been possible to adapt electrolysis processes to commercial applications due to the fact that the amount of electricity required to produce practical amounts of hydrogen has to the present been prohibitively expensive.